CONWAY — Authorities say they have made progress in the missing person case of Abigail Hernandez, but they still need to keep parts of the investigation secret, especially because the case, now two months old, has become unusual.

Senior Associate Attorney General Jane Young, was responding to recent criticisms of authorities' handling of the case, said that missing persons cases always draw heavy law enforcement responses, and the case of Hernandez, 15, is no different.

"People have to ask themselves, what would you want if your 15-year-old was missing? This is our response for a missing child; it's been the same for many previous cases, each case is different, but we always bring all the resources possible to find people."

Abigail disappeared on Oct. 9. Officers from the FBI, state police, the Attorney General's Office and Conway police have been looking for her, as has a large group of volunteers who have been using social media, outdoor signs and other means of getting Abigail's face to as many eyes as possible.

Keeping "sensitive" information, such as the contents of a letter that Abigail sent to her mother after she disappeared, is crucial to the investigation, Young said. The letter's existence was only revealed last week because investigators, who are well trained in missing person cases, decided that public exposure might bring more tips in the case.

Despite questions from reporters at the press conference about the postmark on the letter, which would reveal from where it was sent, Young said investigators met and discussed releasing it, but decided against it.

"We are concerned that if we released the postmark, the focus of the searches would shift to that one location, and other people elsewhere would stop looking,"

Though the letter did give hope that Abigail is alive, law enforcement is still concerned for her safety. Aside from the letter, she had a heavy presence on Facebook that "went dark," authorities said, on the day she disappeared; her phone, which she used often, went dead after a last text to her boyfriend at 2:52 p.m.

She was not known to run away from home, Young said.

"This is a very difficult case. This is a 15-year-old with no known source of funds and just the clothes on her back, and she just vanished," she said. "Even if, in any case like this, a 15-year-old leaves voluntarily, whoever is helping or assisting her does not have her best interest in mind."